Add newsletter block to header

I was wondering if it was possible to add a newsletter sign up block to the header of a site. I know you can add it anywhere else on the page but I'd like to replace the Contact button in the header with a Newsletter Sign Up form block instead. Is this possible at all?

You can put the newsletter on a page by itself in the unlinked section of your site, and then put a link to that page on the nav bar. 

Thanks! I was hoping the user could sign up right there without having to click to another page. Just like it's possible in the footer to do that sort of thing. 

You can add newsletter on a page, then use this plugin to create "button to lightbox"