What are the chances that a nobleperson in England could have a FB account?

[Syntinen Laulu]

If you're writing a novel including a baronet character, you need to be aware that 'baronet' is not a peerage title and that a baronet isn't a nobleman. Also that the word 'nobleman' is very rarely used outside history books and technical discussions of nobiliary law, and the word 'nobleperson' doesn't exist at all.

In terms of social attitudes, there would be no difference between the social-media habits of a titled person and any other member of the upper classes. Be aware also that many people with peerage titles have been given them for achievement in political and other careers and so they are not members of the traditional upper class. So your question doesn't relate to anything meaningful in British social habits at all.