Monday’s result leaves the Chairboys seventh in the League 2 table, holding on to the last of the play-off spots.
Wycombe were resolute throughout at Meadow Lane, with McCarthy making a good block in the 33rd minute to deny Adam Campbell.
Wanderers have now gone five games unbeaten in the fourth tier, with McCarthy praising their latest performance.
“We defended really well as a team from the front,” he said. "We’ve got to our target total for the season, which is 61 points, so we’ll regroup and go from there."
In League 1, Jordan Turnbull suffered a heavy defeat with Swindon, as they lost 6-0 away to Scunthorpe United.
Conor Townsend and Jordan Clarke put the hosts 2-0 up ahead of half-time. Hakeem Adelakun, Tom Hopper (2) and Paddy Madden completed the scoring after the interval.