The Sporting Lisbon star has been capped twice by Spain and was a regular feature for La Liga outfit Sevilla prior to his move to Portugal in 2011.
Everton boss Roberto Martinez is believed to be considering a bid as he prepares for the possibility of life without Mirallas, who has been the subject of an approach from Premier League rivals West Ham.
Martinez has reportedly handed chief scout Kevin Reeves the task of finding skilful left-footed wingers, and Capel fits the bill in this regard.
Formerly a Barcelona youth player, Capel’s contract with Sporting expires at the end of the upcoming season, which means that he could be available this summer for as little as £2 million. However, Everton have not yet officially submitted a bid for the player.