Facebook Messenger app now available for Apple Watch
To install Facebook Messenger on your Apple Watch, first you need to install Facebook Messenger on your iPhone. Then, proceed to Watch app > My Watch > Messenger > Show App on Apple Watch (Toggle on).
In addition to gaining Apple Watch support, Facebook Messenger now works with Spotlight Search on an iPhone or iPad running with iOS 9. It also runs with certain multitasking features on an iPad running iOS 9. With the latter, the app will work with Split View, which allows two apps to run at the same time side by side. It will also work with Slide Over, which allows you to swipe an app over an open app already running on the screen.
With the Spotlight Search, you can search for your contacts and conversations from Facebook without having to open the app. This is accomplished by using the ability of the Spotlight Search in iOS to conduct a system-wide search throughout your phone.
source: FacebookMessenger (iOS) via RedmondPie