hubs often do not work but to directly use it would mean a simple USB-C to USB adapter. Apple or Amazon has that. There is also $79 Apple adapter with three ports for video, hdmi and usb. You can use 3rd party, it may feel safer not to and you should always regardless check comments.
The support page has most of the help and answers you need.
http://www.apple.com/support/macbook/accessories/
Ports and adapters for your MacBook (Retina, 12-inch, Early 2015) - Apple Support
Using the USB-C port and adapters on your MacBook (Retina, 12-inch, Early 2015) - Apple Support
Use the USB-C port to connect USB-C devices, or use a USB-C adapter to connect displays and other standard USB devices. With an adapter you can connect:
- HDMI and VGA displays, TVs, and projectors
- Other USB devices such as iPhones, iPads, and iPods for charging and syncing
- Other USB devices such as cameras, hard drives, and thumb drives for transferring data
The Apple USB-C to USB Adapter lets you use any standard USB (USB-A) device or hub with your MacBook. It provides data transfer and power to USB-A devices. For example, you can use this adapter to connect your MacBook to these devices:
- Portable flash drive
- Hard drive
- Digital camera
- Powered USB 3 hub
- USB to Ethernet Adapter
- Lightning to USB Cable for charging and syncing your iPhone, iPad, or iPod touch
The USB-C to USB Adapter supports data transfer at up to 5 Gbps (USB 3.1 Gen 1).
This adapter requires no power to operate. However, devices that you plug into it might draw power from your MacBook, so you should disconnect it when you're not using it.
https://support.apple.com/en-us/HT204303
