He played youth football with local Danok Bat CF before signing for SD Eibar, making his senior debut in the 2011–12 season with the reserves in the Tercera División.

[16] Dani García made the same move; within weeks they were joined by another former teammate Yuri Berchiche, and before the end of the calendar year by the coach from their Eibar promotion seasons, Gaizka Garitano.

[17] He scored his first goal for Athletic on 10 November 2019, netting the 2–1 winner in the final minutes of the home fixture against Levante UD through a volley from outside the box; he also provided the assist for the equaliser by Iker Muniain in the same game.

[18] Having previously been a regular starter, Capa made only one competitive appearance in the 2021–22 campaign under head coach Marcelino García Toral, and that consisted of just a few minutes as a late substitute.

Subsequently, he was highly critical of the manager,[19] and with no agreement reached on a new contract – even after negotiations resumed when Jon Uriarte was elected as the new president and Ernesto Valverde was brought as the new coach – he appeared set to leave the club.