Highsmith grew up in Wilmington, North Carolina and attended Eugene Ashley High School, where he played baseball, basketball and football.

[1] He played middle linebacker and fullback and was named second-team All-Area and first-team All-Mideastern Conference as a senior.

Highsmith was lightly recruited by college programs and only received interest from Davidson and Furman before being offered a spot on UNC Charlotte's team as a walk on.

[5][6][7] He was again named first-team All-Conference USA and was also a third-team All-American selection by the Associated Press as a senior after setting new school records with 14 sacks and 21.5 tackles for loss.

[13] In week 8 against the Baltimore Ravens, Highsmith recorded his first career interception off a pass thrown by Lamar Jackson during the 28–24 win.

[19] In the regular season opener, Highsmith had three sacks and a forced fumble in the 23–20 overtime victory over the Cincinnati Bengals.