Macbook Pro 13" 2011, Samsung Galaxy S3's Headset Mic not working
You will need a Apple special plug for the Microphone to work.

It needs to look like this:



If it is 4 rings kind, then check you System Preference - Sound setting and select the external microphone as input source.

Final check--the pin out:

The original TRRS configuration was created by Nokia and has a pinout of Left Audio, Right Audio, Mic, Ground.

Apple came along and changed their pinout to Left Audio, Right Audio, Ground, Mic.

You could go about trying to find a jack converter that switches the Ground a Pin for your Samsung headset.