bedreiging gedetecteerd via agenda

Welcome! 

You have found the English-language version of Apple's User-to-User Communities. If you can post in English, you will get faster answers with less chance of our making a translation error.

Apple does not have a Dutch-language version of Apple User Communities, but has forums in German and French if either of those work for you:

Offizielle Apple Support Community

Communauté d’assistance Apple officielle

Ik krijg dezelfde melding.

Your phone has not been compromised, it's just a scam message designed to trick you into buying unnecessary software.

Look here -

Delete spam calendars and events on iPhone - Apple Support