Can I use my Google Apps on My IPhone

Whilst you can't install Android apps on iOS almost all have iOS versions available

Now if you mean can you use Google services; Maps, Chromecast , Chrome, Remote Desktop and Docs in the web, Gmail etc.......

All have iOS versions in the App Store

I guess it depends on what apps they are. If they are available from the App Store, then you swhoukld be able to.

Download apps and games on your iPhone or iPad - Apple Support