On your Galaxy Note 4 you can use the LED notification light to be informed about new notifications. But sometimes you need a stronger light, such as the camera flash to function as the notification light for incoming calls or arriving new notifications.
Follow to instructions to learn how to use the camera flash as notification light on Galaxy Note 4:
1. Open Settings and go to the Personalization tab
2. Tap to open the Accessibility settings
3. Under the Categories, tap the Hearing option
4. Make sure the Flash Notification option is marked, so the camera flash functions as the notification light on your Galaxy Note 4