A native of Birmingham, Alabama, Chapman attended Hoover High School under head coach Rush Propst and defensive coordinator Jeremy Pruitt. Probst described him as the best defensive lineman in school history. As a junior, Chapman tallied 65 tackles, six sacks and three tackles, while helping the Hoover Buccaneers to a 14–1 season record. In his senior season, Chapman recorded 97 tackles, 22 tackles for losses, two sacks and an interception. Hoover finished the season as the 6A state runner-up with a 13–2 record, losing the state final 35–21 to Prattville. The only other loss came against Joe McKnight's John Curtis Christian (LA).