President Trump, isolated and watching the clock count down on his time in the White House, spent a few minutes of it on Friday with the C.E.O. of MyPillow, Mike Lindell, who brought some notes with him.

White House officials said nothing came of the roughly five-to-ten-minute meeting between Mr. Lindell and Mr. Trump, which Mr. Lindell said came after he’d been asking to get on the president’s calendar for days.

But notes that Mr. Lindell brought with him, captured by a news photographer as Mr. Lindell waited before entering the White House, sparked hours of concern on social media about what was taking place with a president who as recently as Friday insisted to White House officials that he had won an election that he lost.

In photographs captured by Jabin Botsford, a photographer for The Washington Post, Mr. Lindell held notes in his hand as he stood outside the doorway to the West Wing lobby mid-afternoon on Friday. The notes included a mention of Sidney Powell, the lawyer and conspiracy theorist whom Mr. Trump at one point wanted to offer a job in the White House.

They were only partially visible, but there was also a suggestion about invoking the Insurrection Act, by which a president can deploy active military troops into the streets, and “martial law if necessary.” One line appeared to suggest moving Kash Patel, currently the Department of Defense chief of staff and a Trump loyalist, as “C.I.A. Acting,” which seemed to indicate the top job.

White House press aides were caught off guard by the photos as they circulated on Twitter, and said they had no idea what had transpired.

Reached by phone, Mr. Lindell said that he was carrying notes supplied to him by a lawyer he was working with to try to prove that Mr. Trump was the true winner of the 2020 election. He would not identify the lawyer.

“The attorney said, can you bring these to him,” Mr. Lindell said. ”It was stuff to help the American people.”

Mr. Lindell said that he was seated next to an administration official, who another official later identified as Robert C. O’Brien, the national security adviser. Mr. Trump ended the brief meeting by directing Mr. Lindell to go upstairs to the office of White House counsel Pat A. Cipollone. Mr. Lindell said he showed them material but was sent back downstairs to wait awhile longer.

Officials seemed “disinterested” in what he had to say, Mr. Lindell said.

A second administration official said that Mr. O’Brien was called to the meeting after Mr. Lindell arrived, because advisers in search of someone who could steer Mr. Lindell away couldn’t immediately reach Mr. Cipollone. Among the items on Mr. Lindell’s list was replacing Mr. O’Brien. The national security adviser, seeking to end the conversation, said if there was evidence of what he was saying it should go to the White House counsel, and he steered him upstairs.

Mr. Lindell maintained that the notes he had did not contain the words “martial law,” although the photograph showed it to be the case. He said the “fake news” was stirring it up. An administration official said that the blacked-out part of Mr. Lindell’s notes could be seen when looked at closely, and that they referenced firing Mr. Cipollone. The official said that Mr. Lindell got “loud” while waiting in the West Wing lobby.

Mr. Lindell has been one of the few supporters of Mr. Trump from corporate America who has stayed with him after the riot by Trump supporters at the Capitol complex on Jan. 6, which left five people dead and included chants calling for the death of Vice President Mike Pence. Mr. Lindell appeared on Newsmax, the conservative cable network, the day of the riot and pushed the now-debunked claim that “antifa” protesters had masqueraded as Trump backers in order to cause damage.

And even after President-elect Joseph R. Biden Jr.’s victory was certified, Mr. Lindell continued to insist that Mr. Trump will be inaugurated for a second term next week.

There was no move to fire Gina Haspel, the director of the C.I.A., on Friday or have Mr. Patel arrive at the C.I.A. headquarters to take over, according to people familiar with the matter. And Washington has already become a militarized fortress ahead of Mr. Biden’s inauguration, in order to clamp down on threats of new violence being planned for the day of the ceremony.

But Mr. Lindell’s ability to walk into the Oval Office and meet with Mr. Trump underscored the type of conspiracy theorists who still appeal to Mr. Trump, so long as they are saying what he wants to hear. It is unclear whether Mr. Lindell wrote the notes or if he was passing along someone else’s thoughts.

Mr. Trump has at times considered Ms. Powell too conspiratorial, as she has touted falsehoods about a global conspiracy to rig the 2020 election. At other times, he has welcomed her input.

Right-wing journalists have resumed demands for the declassification and release of documents related to the 2016 election, including material created by Republicans on the House Intelligence Committee, where Mr. Patel used to work.

Ms. Haspel has opposed the release of those documents. However both Mr. Trump and John Ratcliffe, the director of national intelligence, have the authority to declassify the documents, and the White House would not need to force out Ms. Haspel to make the material public.