Wordpress campaign tracking

Hey Warriors!

I feel like a complete dunce asking about this, but here it is...

So I'm comfortable writing code in a couple languages (PHP, Perl, Javascript, etc).

Typically when I create marketing pages or sites in PHP I include some kind of tracking code in my scripts that will track campaigns. Just something simple like a "campaignID".

So say I run an Ad on Facebook. I'd use a URL like myawesomesite.com?campaignID=FB.

Then, in my landing page script, I retrieve that "FB" from the query string, and just pass it along in other links or call to action elements (like a hidden field on a form).

I'm just starting to work with Wordpress, and I'm not sure how to replicate this behavior.

Sorry, I know this seems like a "programming" question, but it's actually aimed at non-programmers using Wordpress... I'm sure you all are tracking your campaigns somehow. How are you passing through your "campaignID" to your forms and whatnot?

I spent some time googling, and didn't see anything "simple", but I feel like I am missing something obvious, like I'm not thinking of the right keywords to search for or something...

Do we need to hack into the php files of a theme, is there a built in way within WP to grab a variable from the query string (I tried a couple expiriments with no luck), or is this an issue needing a plugin solution?

I can handle a PHP hack, but would rather not alter the base php files of the theme, as don't wanna have to worry about theme updates and so on.

Thoughts folks?

Thanks!

Matt