If you’re using your Mac as a media center, either powered by something like Plex or Kodi, you’ve probably got a keyboard or mouse hidden underneath your television or couch. With Remote Control for Mac, you can control your media center from your iOS device using the available trackpad and keyboard in the Input section.
LifeHacker

Macs can make excellent home media centers, but it can be awkward setting up a mouse and keyboard to control it from the couch. It's even harder to pull that off if you're using Apple TV and AirPlay to mirror your Mac from elsewhere in the house. That's where apps like Remote Control for Mac come into play. With it, you can use your iPhone or iPad to type and move the cursor. A recent update even lets you get this all done with your Apple Watch! Let's dig in and see what else this app has to offer.
iMore

Users are able to control volume, playback, and AirPlay mirroring directly from an iOS device. Additionally, the app can morph into a trackpad for a Mac, control any app, launch and quit apps, and more. All of Remote Control's features are included with its purchase price, so no extra in-app purchases are present.
MacRumors