Two men convicted of fraud for targeting Black voters with phony robocalls before the 2020 election must spend 500 hours registering voters in low-income neighborhoods of Washington DC, an Ohio judge ruled.

The calls told people they could be arrested or forced to receive vaccinations based on information they submitted in votes by mail.

Jacob Wohl, 24, of Irvine, California, and Jack Burkman, 56, of Arlington, Virginia – rightwing operatives with a history of targeting Democrats and other public figures – pleaded guilty last month, each to a single felony count of telecommunications fraud.

The judge in Cuyahoga county common pleas court, John Sutula, also fined each man $2,500 and placed them on two years’ probation. They were ordered to spend six months in home confinement, beginning at 8pm each day.

“I think it’s a despicable thing that you guys have done,” Sutula said, comparing their actions to violence used to suppress Black voters in the south in the 1960s.

Wohl and Burkman were indicted in October 2020, accused of arranging for a voice broadcast service to make about 85,000 robocalls to predominantly Black neighborhoods in Ohio, Michigan, New York, Pennsylvania and Illinois in the run-up to the 2020 general election.

Prosecutors said the pair were responsible for 3,500 calls to residents of Cleveland and East Cleveland.

According to James Gutierrez, an assistant Cuyahoga county prosecutor, the robocalls warned voters that police, credit card companies and the federal Centers for Disease Control and Prevention would use personal information obtained from mail-in ballots to find individuals with arrest warrants and credit card debt, Cleveland.com reported.

Some calls told voters personal information would be used to carry out forced vaccinations.

According to a script published by the New York attorney general, Letitia James, one call said: “Hi, this is Tamika Taylor from Project 1599, the civil rights organization founded by Jack Burkman and Jacob Wohl. Mail-in voting sounds great, but did you know that if you vote by mail, your personal information will be part of a public database that will be used by police departments to track down old warrants and be used by credit card companies to collect outstanding debts?

“The CDC is even pushing to use records for mail-in voting to track people for mandatory vaccines. Don’t be finessed into giving your private information to the man, stay safe and beware of vote by mail.”

Gutierrez said: “All of that is false … there is not one kernel of truth into what they said in that recording.”

Wohl told the court he wanted “to express my absolute regret and shame over all of this”. Burkman, a Swissvale native, said he wanted to “echo” that sentiment.

Another prosecutor, Michael O’Malley, called the sentence appropriate, saying the defendants “attempted to disrupt the foundation of our democracy”.

Wohl and Burkman have also been sued in federal court in New York and face a $5.1m fine from the Federal Communications Commission. They are appealing criminal charges in Detroit, stemming from a similar bogus robocall scheme targeting Black voters.

• Associated Press contributed reporting