After going undrafted in the
2017 NBA draft, Caupain signed a summer league contract with the NBA's
Toronto Raptors however, he was waived on October 13. Ten days later, he was acquired by the
Lakeland Magic of the
NBA G League, averaging 15.8 points, 7.5 rebounds, 5.7 assists and 1.4 steals in 51 games. On April 4, 2018, after the conclusion of the G League season, Caupain signed with
G.S.A. Udine of the Italian
Serie A2 Basket. Caupain made his NBA debut on December 31, 2018, in a 125–100 loss to the
Charlotte Hornets, scoring five points with two assists in five minutes of playing time. On September 12, 2019, Caupain joined the
Portland Trail Blazers for training camp. On October 18, 2019, the Trail Blazers waived Caupain. On November 3, 2019, Caupain signed a one-year deal with
Hapoel Holon of the
Israeli Premier League. On December 28, 2019, Caupain recorded 23 points, while shooting 8-of-12 from the field, along with six rebounds and four assists in an 84–91 loss to
Hapoel Jerusalem. On February 6, 2020, he parted ways with Holon. On February 21, 2020, Caupain signed with
Filou Oostende of the Belgian
Pro Basketball League. On July 31, 2020, he has signed with
ratiopharm Ulm of the German
Basketball Bundesliga. On June 30, 2021, he has signed with
Darüşşafaka Tekfen of the
Basketball Super League. On July 7, 2022, he has signed with
Pallacanestro Brescia of
Lega Basket Serie A. On July 13, 2023, he signed with
UCAM Murcia of the Spanish
Liga ACB. On June 1, 2025, he signed with
SIG Strasbourg of the French
LNB Pro A. On June 16, 2025, he signed with
Pallacanestro Reggiana of the Italian
Lega Basket Serie A (LBA). ==Career statistics==