An OTG cable has a USB-A input, a microUSB input, and a microUSB output.
Plug the microUSB output into the back of the camera (instead of the charging cable).
Plug the charging cable into the OTG cable's microUSB input, then plug it into a power outlet. This will charge the camera.
Now you can add other USB devices to your workflow, such as a USB audio device.
You can also use an Ethernet-to-USB adapter to bring in an Ethernet connection.
If you are connecting to Ethernet via this USB workaround, please be advised that you must connect your iOS device to the camera using the Hotspot Mode.
The Mevo app will indicate the camera is connected to an 4G/LTE Modem, however this is simply due to the software recognizing the hardware as a USB connection. Be assured that you are in fact streaming over Ethernet, not data.
It's important that your USB hub be a powered hub, as it would need to provide power to your other connected devices.
Start by plugging your USB hub into a power source.
Then plug an OTG USB cable into your camera.
Plug the USB cable that comes included with your hub into the USB output port (i.e. the one that would connect to a computer)
Plug the other end of the cable into the OTG cable attached to your camera.
On the other end of the OTG cable, plug in your charging cable and connect it to power.
You can now attach more than one USB device to your camera, such as an audio adapter and an Ethernet adapter, or an audio adapter and a 4G USB modem.