I have an iPhone 7 and I have a Google Cardboard that doesn't have a magnetic clicker. I would like to use an app, but it requires me to either tap the screen or use the VR clicker to click. Can I setup some sort of "tapper" on Mac so when I click a key on my Mac it taps the screen of my iPhone? (Software Program)
It's not possible for an application to control an iPhone in this way without jailbreaking due to iOS restrictions.
If the device is jailbroken, you may be able to install a VNC server on the iOS device like Veency and use Screen Sharing on the Mac such that you can click on the Mac and the click will emulate a tap on the iOS device.