phone being hacked?

Not getting hacked no. You inadvertently subscribed to a spam calendar.

Just unsubscribe from the offending calendars.

On iOS, open Calendar. Tap Calendars >  > Delete Calendar.

In the future don't subscribe to random calendars on websites you visit. Pay attention to popups you see.

More details here: link-> Remove spam from Calendar on your iPhone - Apple Support

go to Settings > Calendar > Accounts; look under Subscribed Calendars, tap on the spam calendar and tap delete.

Remove spam from Calendar on your iPhone - Apple Support

Your phone is not being hacked.

You were conned into subscribing to a spam calendar.

Unsubscribe from it.