The Saints defender played the full match, with the result seeing the Chairboys rise from tenth position in the table to sixth.
It looked as though Wycombe might be in for a comfortable night against the struggling Daggers, as Paul Hayes tapped in to put them 1-0 up on the stroke of half-time, shortly after Josh Passley had been sent off for the hosts for bringing down Garry Thompson when he was through on goal.
But Thompson himself was dismissed for the visitors on the hour mark, for a high tackle on Joss Labadie, and it looked like it wouldn’t be the Chairboys’ night when Luke Guttridge eluded centre-half McCarthy in the area to nod home an equaliser in the 72nd minute.
Yet parity lasted for only a few moments, as a Sam Wood cross was headed in by Paris Cowan-Hall, with McCarthy and the rest of the Wycombe rearguard then able to ensure the lead remained intact.
Elsewhere last night, Gastón Ramírez made his first appearance for Middlesbrough, as they drew 1-1 away to MK Dons.
Ramírez started and played most of the game, before being substituted in the 85th minute, going close with an early shot from 25 yards that fizzed a yard or so wide of the post.
It was MK Dons who struck first, though, with Dean Bowditch turning to fire in a shot after nine minutes.
It looked as if that goal would be enough to earn the hosts all three points, with Ramírez being denied in the second half by keeper David Martin after playing a clever one-two with David Nugent to get through, but Jordan Rhodes headed what could be a vital equaliser for Boro in added time at the end of the game.
The result means Middlesbrough are now without a win in four league games, but the point was enough to move them above Hull City and back into the Championship’s top spot.