noVNC is a HTML5 VNC client that runs well in any modern browser including mobile browsers.
The recommended way to run this container looks like this:
$ docker run -d -p 6080:6080 colinhuang/ubuntu-novnc-armhf
This will start a container in a detached session in the background and will expose its web interface to port 6080 of the host. Now you can browse to:
to access the Ubuntu desktop.