Microphone / Headphones combo port does not work in BootCamp I have an iMac (27-inch, Late 2013) that has a 4-pole TRRS headphone/headset combo port. 
On OS X any  headset works nicely (e.g. the Apple iPhone headset with microphone). 

On Windows 7 64bit with BootCamp 5.1, 
the same headset on the same combo port does not work with the driver as delivered by Apple with BootCamp 5.1 (more precise: 5.1.5640 ).
Apple phone support just told me it is not their problem, 
because it works on OS X.
So I tried installing a better driver on my own.

According to the Windows Device Manager, 
my sound card is a Cirrus Logic CS4206B (AB 07). 
The closest match I could find on the Cirrus homepage was this one:
http://www.cirrus.com/en/products/cs4207.html
(Go to Resources -> Tools and Software).  

The same page is also linked in this related thread, 
including a step-by-step installation guide, 
but it doesn't work for me. 
Did someone get a 4-pole headset to work including the microphone on an iMac with the Cirrus Logic CS4206B (AB 07) sound card?
Not sure if people are still having a problem with this as it's been almost a year, but I was running into this problem with my Mac mini 2014 with Windows 10 Home and Bootcamp v6.0.
  The sound card is Cirrus Logic CS4208 (AB 108), and I couldn't get Windows to recognize the mic on my headset which was designed for iPhone/Apple usage.

After not being able to find the driver for the CS4208 (AB 108) at a legitimate site on the net (results almost always required a 3rd party driver downloader - no thanks!), I went to Cirrus Logic's website and tried to search for another driver.  I was able to find CS4207 from their website, downloaded the zip file, and tried to update the CS4208 driver with files on this zip.  The driver was taken, and, after a restart, the microphone now showed up (even though it was still showing CS4208 AB 108).  It works!

I even rolled back the driver and updated again to confirm it works, and it sure does!  I also have another 2016 MBP that I would like to test.  Will update here after.

Here's a few screenshots before the driver update to CS4207:


And after updating the drivers and restart: