Read value or file in G-code

Hello, I want to use QtDragon to determine the tool height using Utils - Workpiece and then save the result so that I can access the value in the G-code. My idea was to save the result to a file, which also works by slightly modifying the auto_height.py file. I added the following line:

def show_result(self, data):
        diff = float(data) - float(data)
        self.lineEdit_height.setText(format(diff, '.3f'))
        # New line by me:
        with open('/home/dg/linuxcnc/nc_files/probe_height.txt', 'w') as f: f.write(str(diff))

But how can I access the value stored in the probe_height file in a measurement routine.ngc, or can I save the measured value directly in
the G-coder as a variable, e.g., #5000