If Siri wasn’t activated while setting up your iPhone, you can activate it by opening Settingspressing Siri & Search and then turning it on. You’ll want to ensure Press Home for Siri is toggled on.

Siri is your personal assistant, and can be used to control certain functions on the phone by using voice commands. To access Siri, press and hold the Home button for a few seconds until the microphone icon appears, and then start speaking after you hear the double-beep.