The Gabonese had fallen behind to Youssef El-Arabi's first-half penalty but, just after the hour mark, Evouna worked his way past several Moroccan defenders and produced a calm finish to earn a draw for his side.
Both sides had interim coaches at the helm and after a cagey opening, Morocco captain Adel Taarabt fired a warning shot, sending a curling effort over the crossbar from 25 yards in the 16th minute.
The visitors responded immediately, Evouna testing Mohammed Youssefi with a strike from the edge of the box soon afterwards.
In the 27th minute, the home side were handed the chance to break the deadlock. Bruno Manga brought down Abdelaziz Barrada inside the box and El-Arabi struck a low penalty into the bottom left-hand corner.
With half-time approaching, Gabon went close to an equaliser, Frederic Bulot's deflected free-kick wrongfooting Youssefi, who was lucky to see the ball fly just over the crossbar.
Bulot wasted great chance to equalise 10 minutes after the break, firing off target from eight yards with just the goalkeeper to beat.
Evouna's superb finish rendered that miss irrelevant five minutes later though, the striker picking up a loose ball before beating three men inside the area and slotting a cool finish beyond Youssefi.
Taarabt almost won it for his side 12 minutes from time, but his low free-kick was tipped onto the post by Didier Ovono and bounced away to safety.
