Navigate to the ExAM Configuration tab. Here you will see the Assess Anything section.

Here you will click the Drop-down Picklist and select the Object that you wish to make assessable (All objects that aren’t already assessable will be shown in this field). Then you will click Create ExAM to Object and the object you selected will become assessable.

You are able to repeat this process for any standard Salesforce Objects as well as any Custom Object that you have in your Org.