The Chairboys came from a goal down at Wham Stadium to earn a point that lifted them up to seventh place in the table, above Leyton Orient on goal difference.
Accrington, who are fifth in the table, broke the deadlock right on half-time, as Shay McCartan skipped through and delicately lifted the ball over keeper Ryan Allsop.
McCarthy, playing at right-back, made a crucial intervention ten minutes after the interval, with the 20-year-old brilliantly clearing Piero Mingoia’s low delivery across the six-yard box before Billy Kee could tap in at the far post.
It proved to be a vital moment, as Gareth Ainsworth’s side equalised in the 62nd minute, when Gozie Ugwu’s deflected shot from distance spun into the path of Garry Thompson, who struck the ball low into the bottom corner.
Wycombe, who have taken four points from their last two games, now travel to tenth-placed Carlisle United on Saturday.