Following his college football career, he was selected in the second round of the 1970 NFL draft by the Minnesota Vikings, serving as a backup quarterback in the 1970 season.

He was traded by the Lions in 1974, played in the World Football League, and was signed on as a quarterback to the Tampa Bay Buccaneers in 1976.

[3] As a high school athlete, he visited Florida State University in Tallahassee, Florida, and was impressed by the pass-heavy, pro-style offense that head coach Bill Peterson had implemented with quarterback Steve Tensi and wide receiver Fred Biletnikoff.

[3] Cappleman attended Florida State University from 1966 to 1969,[3] playing at the quarterback position for the Seminoles football team in his last three years.

[2] The Seminoles finished their regular season with 8 wins and 2 losses, as well as a berth in the 1968 Peach Bowl.

[9] Cappleman served as the quarterback for the bowl game, which the Seminoles lost by a score of 31–27 to the LSU Tigers.

[12] During all of his playing seasons with the Vikings and Lions, he was a backup quarterback, with sportswriter Skip Rozin describing his career as "frustrating".

[5][17] In recognition of his performance during the Seminoles' 1968 game against the Houston Cougars, Sports Illustrated named Cappleman the "national back of the week".