Noted

If writing in a journal isn’t really your thing, or you just want to be able to take notes in an instant, then Noted is the right app for you.
Noted is pretty simple to use. All you need to do is click on the icon on the menu bar, and start typing. Your notes will save after you’re done, even if you close the app or restart your Mac.
Plus, all your notes will be stored locally on your Mac, so you don’t have to worry about anyone or anything accessing your notes without your permission, not even the developers of the app.