Outlook: How to detect Appointment/even save and have callback function

I’m developing an Outlook Add-in that includes a taskpane with a form. When a user opens an appointment or event and launches our app, the form loads. We need to validate the form when the user clicks Save or Send. If the validation fails, we should prevent the save/send action and display an error message.

I found the OnAppointmentSend event in the documentation, which seems to work for the Send action but not for saving an appointment. Is there a way to implement this for both actions? Please let me know if you need any additional details.