Get ResponseHeaders from website to Postman

Good afternoon, I'm making requests to a site and I need a token, in RespondeHeader the token appears, but with all the requests I make, that token changes. How do I get the token value in Postman to make an environment variable to use, so I do not need to get ctrl + c in the token in the site and ctrl + v in Postman all time.

i try responseJson.responseHeaders.

responseJson.responseHeaders.x-access-token

responseJson.responseHeaders.get("x-access-token");

no working, i try console but the result is null or error.