You should promptly contact the company to ask for ways to return the laptop as soon as possible. You should have returned that laptop on your last day of work.

**Please pick up the phone now (today), and call HR,** or the hiring manager, or recruiter, or the IT department. Some of them will definitely point you to the right person to return the laptop. 

In addition to making the phone call, you can also send them an email to have a paper trail in case they accuse you of intentionally not returning the laptop. But, emails tend to be slow or can even get lost. So, make sure you call first, and send a follow-up email if necessary.

This MacBook Pro laptop an expensive laptop. But, even if they gave you a cheap laptop, you should still return it ASAP as this is a matter of being professional and responsible.

The longer you keep it, the more likely the company may have unfavorable opinion about you. If they have to track you down to ask for the return of this laptop, they may not even want to offer you the second term of internship the next time.