Is there any way to use bbcode in Facebook? Like the [s] tag for
strikethrough . Or simple HTML link. I saw few pages using links and strikethroughs so I wonder how do they use these features?
No, you can't use markup of any sort in Facebook posts. For strikethrough they're probably using high-ASCII characters.
Pages may have more tools available to them, especially if they're advertisers (i.e., paying for the privilege).