As ads or promoted posts, zero. Through Facebook pages, well, quite much, with varying degrees of success. Extreme presidential candidates last year (Mélenchon for the far-left and Le Pen for the far-right) had I think the best participation numbers online, and a pretty good YouTube strategy (almost daily explanatory videos). Fringe candidates (Asselineau, Dupont-Aignan) are also quite good online. Our current president, Macron (liberal in the non-American sense of the term), also had a good online strategy, but the other candidates were forgettable at best.

You're not limited on what you can do on a political Facebook page, as long as you don't pay for promotion, respect expression rules (no defamation or hate speech), and stop campaigning two days before election day.

edit: replaced discrimination by defamation; still not sure about the translation but I think it fits more