The easiest way to track clicks on an image that links to another webpage is to make that image a Call-to-Action using HubSpot's Call-to-Action button builder. To create your CTA > navigate to Content > Calls-to-Action > Create a CTA and select Custom Image for Button Type. Once the details for the CTA have been saved you'll be able to embed the new CTA on your website pages and easily track clicks, submissions, and other analytic data.
HubSpot Enterprise customers also have the option of creating custom events to track clicks on their website. To configure an event for an image click in your portal navigate to Reports > Events > Create a New Event. Choose Clicked Element for the Type of Event, and fill out the relevant information.