We have searched the ESPaDOnS archive for all data on M dwarfs, and homogeneously explored the activity and magnetism diagnostics on this data set. A total of 446 stars and 1878 spectra have been analyzed. Chromospheric activity signatures, circular polarization (when available) and Zeeman broadening of FeH lines are investigated. We tried to define a scale for activity in the objective of selecting the most favorable stars for exoplanet search with SPIRou.