In an entertaining opener Carlisle gave a confident opening account of themselves and on 17 minutes found the net. Good work from Zigor Aranalde on the left flank gave Derek Holmes the opportunity to turn and shoot past the diving Frank Talia.
Wanderers, undeterred after falling behind, remained calm and pushed forward with the experienced Mooney and highly-rated youngster Nathan Tyson.
The breakthrough came on 37 minutes for Wanderers when, only seconds after Peter Murphy cleared off the line for United, Mooney made an early claim for goal of the season.
The former Swindon front man produced a wonderful curling shot into the top corner from 25 yards giving Anthony Williams no chance and delighting the home fans.
Wanderers pushed forward and minutes before the break captain Roger Johnson twice hit the woodwork. His first effort was a volley from the edge of the area, which was closely followed by a guided header that again crashed against the bar.
The second period saw the home side continue their push for the winning goal. Mooney forced Williams into another fine save and Stefan Oakes came close for Wanderers with his 35-yard free kick.
Carlisle were limited in their chances and Holmes should have done better with his header from an accurate Brendan McGill cross.
Wycombe boss John Gorman must have known it wasn't going to be his day when Kevin Betsy struck the woodwork for the third time from his low shot.
Despite good possession Wanderers failed to capitalise against an organised Carlisle rear-guard and a shared point on the opening day would please Simpson and the United faithful more than Gorman's promotion favourites.