The Patriots did not respond with comment from Caserio at the time of publication of this article.
"I've been in shape and ready for this for 3 years, can't wait to see the head coaches and GMs on Saturday", Kaepernick said.
Kaepernick began kneeling during the national anthem to protest police brutality and racial injustice in 2016.
Kaepernick jumped to Twitter to reveal his excitement for the workout, but he also confirmed that he was not included in the plans until the workout was already set and announced.
Colin Kaepernick #7 of the San Francisco 49ers looks on from the sidelines during the second half against the Atlanta Falcons at the Georgia Dome on December 18, 2016 in Atlanta, Georgia.
Which team would you like to see sign Kap?
NFL Network's Ian Rapoport added that "several clubs" have expressed interest in Kaepernick.
Kaepernick, who led the 49ers to the Super Bowl in the 2012 season, reportedly has continued to work out in hopes of returning to the league.
Kaepernick became a free agent in 2017. The 49ers said they would not have kept Kaepernick under the terms of that contract and would have released him if he hadn't opted out.
Kaepernick and the National Football League came to an agreement on the workout to make sure that top-level officials were coming to the event, TMZ Sports reported, citing multiple sources.
Kaepernick's representatives have repeatedly said that the quarterback is ready to play for a team again and last month debunked what they called "false narratives".
He and Kaepernick then filed a collusion grievance against the NFL, alleging that the league and its 32 team owners - influenced by President Donald Trump's inflammatory remarks about kneeling players - colluded to prevent the pair's employment.