Is there away to track or report when users CLICK an image which opens another website?

I have a community resource page, and would like to track/prove that visitors are clicking on web banners I'm posting for advertisers. These are banners I'm inserting on my website, not google ad's. I'm behind the times in knowing how I can prove the traffic conversion to the advertiser's website, if they are not tracking stats with their own program. - thanks -