Beta testers who have signed up for Apple's beta testing program will receive the iOS 9.2 update over-the-air after installing the proper certificate on their iOS device.
Those who want to be a part of Apple's beta testing program can sign up to participate through the beta testing website, which gives users access to both iOS and OS X betas. Because iOS 9.1 was just released, it will likely be a month or more before we see the public release of iOS 9.2.
iOS 9.2 fixes several bugs in the operating system and it includes other under-the-hood enhancements. According to the release notes for the first beta, the Safari View Controller (the view of Safari you see within apps) is being updated with support for third-party Action Extensions that will let it more closely mirror the Safari app. It also includes options to reload content and request a desktop site, as in Safari.
Article Link: Apple Releases First iOS 9.2 Beta for Public Beta Testers