CHF8.60 per piece for 2 units
Apple USB-C Headphone Adapter
Question about Apple USB-C Headphone Adapter
And if you connect a headset with a microphone, does the sound only go out or also in via the microphone when telephoning?
Unfortunately, I don't have such a headset, so I can't judge it. But if it works with the normal jack of older iPhones, it should also work with newer ones with this adapter.