Google Now On Tap was announced during this year’s Google I/O in May and with just a long press of the home button, it essentially tries to give you information about certain elements in any app. However, the down side was that it was supposed to be exclusively for Android 6.0. Not even the developer previews had access to this feature, until now.
Google has released a new update to the Google App, which fortunately brings Google Now On Tap to the 3rd and final Android M developer preview. I played around with it myself and it works quite well on Chrome. Other changes in the update include the move to the vertical app and widget drawer
You can grab the app update itself from the source link below. Now all we have to do is wait for whenever the official Android 6.0 builds are released.