Itsycal is a tiny calendar for your Mac’s menu bar. It adds one function that has been missing on the Mac from day one, and one that has driven me crazy for years.
Itsycal will display a monthly calendar, as well as your calendar events from the Mac Calendar app. Events are highlighted on the calendar, and you can also create and delete (but not edit) events.
Itsycal is a lightweight app and is free of charge.