iMovie app deleted on iPhone

BTW, you are in the wrong forum.

Mac apps cannot run on iOS devices.

I'll ask the moderator to relocate your post.

Did you try

App Store app > Updates > Purchased > here?

Note: You must have Wi-Fi Internet connection to download (You cannot use cellular data).

Log in to the App Store with the user ID you purchased it with and re-download it.

Open the App Store icon on your device, click on the Update option at the bottom, then on Purchased>My Purchases>Not on this Phone, find the app and click on the little cloud next to it to re-download it.

Cheers,

GB

Did you purchase it from the App Store originally? If so make sure you are signed into the store with same ID as when you bought it.