If you're a student or creative that uses iPad to work, Amplenote offers built-in drawing in any note:

The drawing tools offered are the standard set that Apple provides:

open_in_new

Drawing is not yet available on non-iPad platforms, but could be added by request on the feature voting board.

linkContinuing to edit a past drawing

To continue editing a previous drawing, tap on the image, then tap the Amplenote drawing icon to continue making edits to your image.