I want to capture duration of an request in my script. Can Customer_Measurement help my req? Pls share sample code

When I do a test run for 250 users, I want to capture the duration time for a specific request into a variable and later I can write that variable in to a external file.

Note: I know how to write a variable to external file. I am not sure how to capture the duration. Can Custom_Measurement action help ? if so can anyone share sample code to achieve same. Thanks