Do what Edward Snowden does: physically remove the microphone circuitry from your phone, then plug in earbuds if you ever need a microphone to talk on the phone, etc.
I'm guessing he probably didn't buy the new iPhone 7...
Now there's an interesting thought. How much access do the new headphones have to the rest of the device - they're not just a simple analog connection any more. Do they have DMA?
I'm guessing he probably didn't buy the new iPhone 7...