Rain forced an adjustment of Zimbabwe's original target of 176 for victory to 129 off 30 overs, but, whether through complacency or carelessness, they lost three middle-order wickets in four balls before Maruma's spectacular effort put them back on course for 3-wicket victory.
The home side were struggling on 118/7 when Maruma produced his heroics as the hosts got over the line with five overs to spare.
Earlier, the visitors stumbled to 175 all out in 47 overs after surprisingly opting to bat first in overcast conditions.
Kyle Jarvis, Chris Mpofu and Sean Williams were the chief destroyers as they took two wickets apiece as the UAE batsmen once again put on a poor showing for the fourth game.
This was the fifth clean sweep Zimbabwe have accomplished in a bilateral ODI series.
The first, and most memorable came against England in 1996/97, and they also achieved this against Bangladesh twice in the early 2000s and against Kenya in 2008.