Make sure your phone/tablet and Chromecast are connected to the same Wi-Fi network.
Open the Google Home app on your phone.
Tap the Chromecast you want to mirror your phone to.
Tap Cast my screen.
Tap Cast Screen
Google will warn you not to show any passwords or other sensitive data while screen recording or casting your screen. Tap Start now to cast your screen to your Chromecast.
You can control the volume in the Home app and also tap the Stop mirroring button when you're done.
And that's it! When you're done casting your phone to your TV, you can find the controls for turning off screen casting in the Google Home app or in the notification shade on some phones (pull down from the top of the screen).
From an iPhone or iPad
With AirBeamTV’s app for Chromecast, you can watch anything from your iPhone and iPad on your television screen. Please note - although you can try this for free we have to give you a 'heads-up' that you're going to be presented with an option to pay for a subscription or make a one-off payment to unlock 'Unlimited Pro Mirroring'. If you don't want to go down this route there are other options for connecting iPhone and iPad to your TV here.
Make sure that your iPhone or iPad runs on iOS 12 or higher and is connected to the same WIFI network as your Chromecast device