Although Facebook has not yet officially announced the new dark mode option, the news has been disclosed by very reliable sources.
Jane Manchun Wong, serial leaker and app reverse engineer, disclosed the news along with a video made in collaboration with the tech communications manager of Facebook, Alexandru Voica.
Facebook is publicly testing Dark Mode! 🌙
— Jane Manchun Wong (@wongmjane) October 30, 2020
Unfortunately, there is no way to guarantee that the dark mode will be activated on smart phones currently as it is still a test. Facebook appears to be rolling out the feature to a few selected users. There are no tricks you can use to make the option shows up for you as it is controlled server-side.
In order to check whether dark mode is available, one can open up the social media app and head to settings. In the ‘Settings & Privacy’ section, the option to go dark can be enabled – if not, you’ll have to be patient.