HI,i am now to the Duet Family i have just upgraded my flsun to have a duet2

I want to ask I have seen that you can create conditions where you can use an if statement

like if !move.axes[0]

is there a list of the variables as i want to create an if statement
to detect if the level probe is still connected
so it can not start printing when it is still connected

as this will make the probe crash into the bed

when my probe is connected on the dashboard the Z-probe is read and reading 1000

is there a way of reading this and creating a condition using
something like

if sensor.in (what ever is the z-probe)