Born in
San Sebastián,
Gipuzkoa, Capilla joined
Real Sociedad's youth setup in 2010, aged 15, after starting out at
Antiguoko. While still a junior, he made his senior debut with
the reserves on 10 November 2012, coming on as a second-half
substitute in a 2–2 home draw against
SD Logroñés in the
Segunda División B. On 27 November 2013, Capilla was called up to train with the main squad. He was promoted to the B team on 23 June 2014, and renewed his contract on 1 October 2014 until 2020. Capilla made his first-team – and
La Liga – debut on 1 May 2015, replacing
Carlos Vela in the dying minutes of a 3–0 home win against
Levante UD. On 17 July of the following year, he was loaned to
Segunda División side
CD Numancia for one year. On 15 August 2018, Capilla joined third-tier
Cultural y Deportiva Leonesa on a
season-long deal. In July 2019, upon returning from loan, he moved abroad after being transferred to Greek club
Asteras Tripolis FC. ==Personal life==