How to get from Paris Charles de Gaulle Airport to Paris Gare du Nord?
Take the RER B train
https://www.parisaeroport.fr/en/passengers/transport-parking/public-transport-paris/rer-b/cdg
or a taxi from the official airport stand.
https://www.parisaeroport.fr/en/passengers/transport-parking/taxi/cdg
Taxi fare is fixed from CDG. I’ve not particularly enjoyed taking RER with baggage. The choice is obvious for me.
That fixed fare is currently 56€ for up to four passengers in case you need that information. The train costs 13€ per adult.