The declaration is required when the move leads to both leaving:

• a perimeter defined by a circle with a radius of 100 km around the place of residence (the distance of 100 km is therefore calculated "as the crow flies"),
• of the department.

It is not necessary to bring the declaration:

• for trips of more than 100 km made within his department of residence.
• for trips outside the department of residence, within the limit of 100km.

More information: https://www.interieur.gouv.fr/Actualites/L-actu-du-Ministere/Deconfinement-Declaration-de-deplacement