To leave a private note on a draft or a published post, select some text and click the lock 🔒 icon. If you do not see this option in the toolbar, it is because the author has turned off private notes.
Notes will only be visible to the person who left the note, and the original author. If the post is in a publication, the editors of the publication can also see the note.
Private notes on your posts can be turned on or off on the Settings page.