Use APKPure App
Get N-ify for Android old version APK for Android
Several features introduced in Android N on your Lollipop or Marshmallow device!
If you want to try Android™ O features, then you can download O-ify app: https://goo.gl/6gEbcu
Your device doesn't get an update to Nougat or you are just too impatient to wait? Then this module is what you need! Android N-ify allows you to use many of those new fancy features on older devices.
Author: MrWasdennnoch@xda