Hey I am seeing display of messages in Calendar event saying that my phone is hacked and recommending to install a security app what’s this

Are you seeing something as shown in the pic below? This is neither a hack nor a virus. It is spam and you can get rid of it. Read below...

Then probably you have accepted an offer or subscribed for a spam Calendar accidentally. Watch the GIF below to know how to unsubscribe from these alerts. Look for an unknown Calendar on the device under subscribed calendars.