Dunk's late header secures three points for the U's
United began the first-half well on top of proceedings, Kwesi Appiah forced Scott Flinders into a good save on two minutes and Michael Nelson headed inches over the bar from the resulting corner.
The U's had a penalty appeal turned down in the tenth minute, Appiah going down in the box, just before Liam Hughes curled his shot wide from 20 yards out.
Greg Taylor's low cross in the 13th minute was somehow not converted by United, the visitors managed to clear the danger. Appiah came close again for the U's on 25 minutes, he headed Tom Elliott's cross into the hands of Flinders.
One minute later and United were in front. Michael Nelson's through ball found the feet of Ryan Donaldson, who raced through and fired past Scott Flinders.
The U's came close again through Elliott and Chadwick, the visitors' best effort came from Jonathan Franks, his shot from 25 yards ending up wide of Dunn's goal.
HT: U's 1-0 Hartlepool
The second-half began with the visitors on top of proceedings. With Marlon Harewood introduced at half-time, Hartlepool came close on 49 minutes, Matt Crooks firing over from close range.
Michael Nelson nodded over from a corner for United on 56 minutes before the visitors levelled. After some good work from Harewood down the left, his ball found Brad Walker on the edge of the box and he smashed home past Chris Dunn.
Tommy Miller's shot from range ended up just wide on 70 minutes, before Elliott and Appiah were both denied by blocks in the Pools' area. United left it late and it was Harrison Dunk, on his birthday, who nodded in the winner on 87 minutes after Tom Elliott had flicked on Liam Hughes' throw-in.
FT: U's 2-1 Hartlepool
TEAM: Dunn, Tait, Nelson, Coulson, Taylor, Champion (Dunk, 67), Chadwick (Naylor, 59), Hughes, Donaldson, Elliott, Appiah (Simpson, 88).
Not Used: Norris, Lanzoni, Lennon, Bird.
ATT: 4,931 (195),