Use a universal remote to control Apple TV
You can use any infrared remote to control Apple TV. You just need to let the other remote learn the signals that the Siri Remote generates.
Teach an infrared remote to control Apple TV. In Settings , go to “Remotes and Devices” > Learn Remote, then follow the onscreen instructions.
You can also use the Siri Remote to control the power and volume of your TV or receiver. See Control your home entertainment system with the Siri Remote.