To link an image on your site, visit the page you wish to add the image to. In the WYSIWYG/editor, add the image by clicking on the media icon as shown below. After successfully adding your image and the Alt text for screen readers, click on the new image followed by the Hyperlink icon as shown below, to enter the URL of the site you wish to link to.
You can link an image to any internal or external link. This Image of Nassau Hall is an external link as it takes you to the Main Princeton University home page.