My phone has been hacked from another people

No, your phone has not been hacked.

If running iOS 13 or earlier versions, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

Go to Calendar app, then click Calendars (middle bottom of the screen) and find the rogue one, click it, scroll down and delete it

Just go to the calendar and delete the subscription.

It happened because you accepted an offer from a web site to “Send Notifications” or other such free offer. You can get rid of it by following the instructions posted above. You can prevent it happening again by not accepting free offers.