Grab featured image from page when sharing on facebook

Hi there,

I was wondering on how to make sure that when people share the link of a page (Like on a facebook wall), it will show the featured image that is dedicated to that page.

So that every page has their own featured image when shared on facebook.
Using the default featured image in WordPress doesn't do anything to accomplish this.

Do I NEED to use a plugin or can I just use the Custom Fields?
(I rather don't use an extra plugin for this, if possible).