Thanks, if i try to change the social_facebook value in website frontend, how to reflect that in backend.

Display using means it get value from backend and changing it while in edit mode will automatically reflect that in backend.

I had changed the content value in front value but it is not changing the value in backend

By the way if i want to display value of some some other object value what should i need to do?

Are you using Share snippet defaultly provided?It doesnt using .

For using other object data, you need to make related widget and controller.You can see live example in website_event module .Go through '/event/get_country_event_list' route in website event.