Use the Nikkai USB-C to 3.5mm Headphone Jack / USB-C PD Charging Port Adapter to plug your existing headphones with 3.5mm jack into your USB-C device. The 3.5mm jack is for Audio only but there is also a USB-C Qualcomm 3.0 Power Delivery 18W Charging Port to Charge and sync your device at the same time. 

Works with all devices that have a USB-C connector including iPhone or Android smartphone. Small, and discreet size.