The name of the praetorian prefect Macro, who (according to Tacitus and Cassius Dio) was driven to suicide by Caligula in 38 AD, is rendered as Macron in French. Thus, it fully coincides with the name of the new president of the French republic.
This -n pattern also applies to Polish and Russian, which apparently borrowed Makron from French or Italian (Macrone). Spanish has Macrón, almost identical to the Russian localization. The same pattern appears in Platón and other Greek and Roman names.