Uber Pop service has been withdrawn within France. Uber X continues as a private car service but prices are similar to those of taxis with the exception of Uber's surge pricing which often makes Uber X more expensive than taxis.
Parisien Taxis are available from taxi stands, but you can hail a taxi from the street if the its green available light on the top of the car is illuminated. There are also taxi apps you can use just like the Uber app.
From the airports, trying to agree upon a pickup location using Uber can be problematic. It's much easier to take an official taxi from the queue or take the bus (Roissybus or Air France bus) or the train.