In the printer profile there is a check box for heated chamber. This will turn on the display in the temperature graph. This is support for a firmware based chamber.
Marlin has M141 and M191 commands to set (and wait for) the chamber temperature and M105 will report the chamber temperature in addition to the other temperatures it reports.
If your printer / firmware doesn't support a heated chamber, then you can use the plugin like the one @Ewald_Ikemann pointed out.
If you wanted a do it yourself solution, you need a printer controller board with room for another thermistor (or other temperature sensing probe), another set of heater terminals, and you would have to be able to build your own firmware.