How can you find out if there is insurance carrier and who it is?

From whom are you seeking this information from, and what stops you from asking them directly?

What is the basis for asking? Auto accident? Health issue, Liability issue?

If you have a claim against them, then you know who they are and at least their name.

In the USA at least... if you don't have ANY of that information.. it sound like you are preparing to commit insurance fraud.

We need more information as to the circumstances here.

You listed this under real estate, so I will assume you mean house insurance.

First a person may not have it, and normally they are not required to tell you. They must supply copies to the lender or if a landlord requires a rental policy.

You can ask them, and ask to see a copy of it. But really can not make them tell you.