Colin Kaepernick hasn’t played in a professional football game in nearly a decade, but the former star quarterback is STILL training for his NFL comeback … this according to his longtime partner Nessa Diab.

TMZ Sports caught up with the radio and TV host this week in New York City … when we asked about Kap, who remains a free agent, as several NFL teams are still without a QB.

Nessa — who had a child with the former 49ers quarterback in 2022 — told us Kap’s busting his ass in the gym, training regularly, hoping an NFL GM will give him a shot to show he’s still got what it takes to lead a football team.

Kaepernick last worked out for an NFL squad — the Las Vegas Raiders — in 2022. The team didn’t sign Colin. Before that, he was invited to a Seattle Seahawks workout sesh in 2020.

The 37-year-old also organized a workout at a high school in Atlanta, where scouts from seven NFL teams showed up to watch him throw.

Last year, Kap was offered a job with the Los Angeles Chargers … however, it wasn’t as a player, but instead as a coach. CK, who would’ve been working for his former HC Jim Harbaugh, chose to pass on the opportunity.

Of course, before his kneeling protest made him arguably the most polarizing player in the league, Kaepernick was a successful starting QB … who even led his 49ers squad to a Super Bowl in 2013.

The Niners lost to the Ravens.