Unbeaten leaders Nigeria moved to 10 points from four matches in Group B and a home win over Zambia on October 7 will clinch a sixth World Cup appearance.
Dropping two points at home eliminated seven-time World Cup qualifiers Cameroon as only group winners go to Russia and they trail Nigeria by seven points with two matches to play.
The draw came three days after Nigeria thrashed African champions Cameroon 4-0 in Uyo — a result that prompted losing coach Hugo Broos to make four changes.
Among those dropped were striker Aboubakar and winger Christian Bassogog, whose second-half introductions lifted the “Indomitable Lions” and put pressure on the “Super Eagles”.
Simon scored with a close-range shot past goalkeeper Fabrice Ondoa after a low cross eluded several Cameroon defenders.
A collision between Arnaud Djoum and Nigeria goalkeeper Ikechukwu Ezenwa led to the spot-kick, and Aboubakar scored with a shot into the middle of the net.