Paul Hayes, who had earlier headed against the bar, shocked the Premier League side with a sweetly struck left-footed volley to put Wycombe ahead.
The captain grabbed his second from the spot to double the visitors' lead.
But Son's deflected effort on the hour and a Vincent Janssen penalty four minutes later pulled Spurs level.
Substitute Garry Thompson headed in Myles Weston's cross with seven minutes to go to put Gareth Ainsworth's side back in front.
But a composed 89th-minute finish from Dele Alli pulled Spurs level again, before Son scrambled in a late winner.