Making a measure device to fit on quadcopter

Hi i wish to make a measuring device and placing it on a quadcopter soi can measure at hights that are difficult to reach, but I don't wish to use a  bouncing signal, but use like a pen with sensor in it which can be brought down onto a flat surface to mark the start of a measurement and then moved to new location and do the same, what electrical equipment do I need to do such a thing. 


A microswitch ?

DMTarmey (author)  steveastrouk4 days ago
cheers hadn't thought of that