Ellison denied Gareth Ainsworth's side only their second win in 12 games with a 78th minute header from Andy Fleming's right-wing cross when he beat Matt Ingram from 10 yards out.
The home side had to come from behind after the game's star performer Paris Cowan-Hall maintained his run of scoring against Morecambe with a 41st minute header of his own.
Nick Arnold swung in a left-wing corner and Cowan-Hall ran in front of his marker to divert the ball past Barry Roche and into the top right-hand corner of the goal.
Cowan-Hall had been the game's most dangerous player with several earlier efforts. On eight minutes he flashed a volley just over the bar and drilled two efforts just wide of the target as he seemed to adapt to the conditions better than anyone else.
The home side failed to test Wycombe goalkeeper Matthew Ingram in the first half with their best effort being a free-kick from Tony Diagne which floated over the crossbar.
The Morecambe left-back then wasted a great chance in the 74th minute when the ball fell to him 10 yards out but he failed to find the target when he should have done better.
The closest either side came to clinching the three points was when Matt Bloomfield's late header was cleared off the line by Morecambe captain Mark Hughes.