You want to send a message to the user anytime a moderator edits their profile? Frontend only, backend only, or both? Send an email or a private message? For example on frontend only you could act on onAfterUserProfileSaved and just compare the user id of the user being edit and the user doing the editing. You can do this with the following condition for example.
[user_id] Not Equal To [cb:userdata field="user_id" user="#me" /]