New USB C MacBook - status light for charging without turning computer on
No light is provided on Apple cables, adapters or the MacBook. 

The device makes a quiet charge sound when you connect the USB cord, so unplug and listen for that sound when you reconnect the charging cable. 

It is similar to the sound made when an iPad or iPhone connects.

For those that prefer light to sound, some docks and adapters have a charging indicator, and probably more will follow suit.


https://www.moshi.com/usb-c-multiport-adapter#silver
usb c to usb a cable with charging led
Usb c to usb a adapter with charging indicator