Capela was born in 1994 in Geneva, Switzerland. His parents are from Angola and Congo. He initially preferred soccer, but as a 6-foot-3 13-year-old, his brother suggested he switch to basketball. As a young teen, Capela met Swiss basketball icon Thabo Sefolosha and became fascinated with hoops. At age 15, Capela joined the Chalon-sur-SaA'ne training center, INSEP, in France. His work at the center, located just outside of Paris, led to Capela eventually playing in the professional French league, LNB Pro A, starting in 2012. Capela played two Pro A seasons before declaring for the 2014 NBA Draft.