The striker salvaged a point in the fifth minute of stoppage time with a header from a corner after Ryan Cresswell had headed home from Joel Byrom's free-kick in the first half, with one of just two chances for either side.
Gregor Robertson was shown a second yellow card towards the end and Wanderers capitalised on their numerical advantage with a dramatic finale.
The opening half an hour produced no real chances for either side in a cagey but entertaining start, with both teams playing with confidence but finding their feet on a slippery surface.
As the sun came out, the home side were able to find their rhythm with some decent moves in the opposition half, but the experienced central defensive partnership of Cresswell and Lee Collins handled the threat well.
At the other end, the best opportunity fell to Lawson D’Ath but somehow the former Reading man header over when Chris Hackett found him in space with an inviting cross.
But they made no mistake on 31 minutes when Cresswell rose highest to head home Joel Byrom’s free-kick from the left, beating Matt Ingram with a powerful effort to give the hosts the lead.
The goal didn’t change the pattern of play as Wanderers continued to have more of the ball without being able to penetrate the back four, and the first half drew to a close with neither side able to trouble the keepers.
With no changes for either side at the break, Wycombe resumed strongly and a flowing move set Sam Wood free down the left, but his low cross was superbly cleared by Lee Collins in the six-yard box just as the sliding Paris Cowan-Hall seemed poised to put the ball away.
Alfie Mawson headed over from a deep cross just before the hour-mark, with Aaron Pierre seemingly being wrestled to the ground as the ball came his way, before Paul Hayes glanced a header wide from Jacobson’s delivery.
Gareth Ainsworth made a change on 64 minutes, replacing Matt McClure with Aaron Holloway, before Paris Cowan-Hall drilled over from 25 yards after a smart run to beat two players.
Wycombe were made to work hard for their chances and felt they should have had an equaliser on 82 minutes when Paul Hayes nodded home after Peter Murphy’s header was saved, but a late flag from the linesman brought an end to the celebrations.
There were further complaints from the home side when Peter Murphy headed wide but received a clattering in the process, prompting cries for a penalty which referee Miller declined.
Then on 87 minutes, it was the visiting fans who were in uproar when Gregor Robertson was shown a second yellow card for time wasting, although he claimed he was waiting for a sub to be made.
In the final minute of stoppage time, Jordan Archer tipped Sam Wood's volley round the post and from the resulting corner, Holloway headed home to spark jubilant celebrations around Adams Park.
Wycombe: Ingram, Jombati, Jacobson, Mawson, Pierre, Cowan-Hall, Scowen, Murphy, Wood, Hayes, McClure (Holloway 64).
Unused subs: Richardson, Bloomfield, Lewis, Kretzschmar, Walker, Craig.
Northampton: Archer, Tozer, Robertson, Cresswell, Collins, Mohamed (Richards 67), Ravenhill, Byrom, Hackett, D’Ath (Carter 54), Toney (O'Toole 89).
Unused subs: Snedker, Langmead, Warburton, Moyo.
Ref: Mr P Miller
Attendance: 3,822 (801 from Northampton)
Winning 50/50 Number: 116393
Prize Money: £635.00