Hey Narendra,

Use chatter in field service lightning and track work with the Chatter Feed:
Integrate Chatter into the Field Service mobile app. The Chatter feed gives field service workers, dispatchers, and customers a place for text and content posts.

Enable feed tracking on work orders.
1.From Setup, enter Chatter into the Quick Find box and select Feed Tracking.
2.Select Work Order from the object list.
3.Check Enable Feed Tracking.
4.Click Save.

Having all the information you need is key to resolving customer issues on the first visit. So the app that lets you easily view all of the activity on a Work Order to date. Chatter means real-time collaboration with other colleagues and headquarters is easier than ever. That way even when they are alone out in the field, your technicians are never stranded!
But what would a great mobile app be without notifications to tell you what you missed? Well, you’ll never have to miss an important message ever again. Push notifications alert users to all new Chatter posts related to their appointments. They are also notified about important changes to their service appointments. Now your technicians can pivot on the fly, even when there are last-minute cancellations!

Hope this will help you.
Regards
Diksha Goel
Zen4orce Developer.