Can prospects tell that we're tracking their engagement?

No, prospects cannot tell you're using Mavin.

Here's why: We're simply accessing the "Who viewed your profile" data that LinkedIn already shows you. When someone views your CEO's profile, LinkedIn records it. Mavin organizes that information. The prospect has no idea you're using Mavin any more than they'd know you manually checked your "Who viewed your profile" list.

One important note:

Prospects can adjust their LinkedIn privacy settings to browse profiles anonymously. However, 90%+ of people never change their default privacy settings, which means LinkedIn (and therefore Mavin) can see when they view profiles.

If someone has enabled anonymous browsing in their LinkedIn settings, neither you nor Mavin will see that they viewed your profile.