Trigger Facebook Messenger's Dark Mode with a moon emoji

There's a simple way to activate the Dark Mode feature of Facebook Messenger. All you need is one emoji: this 🌙 moon emoji. Send the crescent moon to anyone in Messenger, exit the app completely, and enter it again. Just head to your profile (the icon on your upper left) and the toggle for Dark Mode should be there. According to XDA-Developers, this works for both Android and iOS.