I carry plenty of thread sometimes encircle a scrape or crossing with thin black thread to determine if anything is passing through. The thread will be broken in the direction of travel.
Years ago before trail cam's I used timers with thread...only trouble is they don't tell you if it is a shootable buck.
When setting in my tree stand I watch a 4 point buck approach a scrape he would get to my timer string stop and look right at the device attached to a near by tree. I thought this is the smartest buck in the world. I watch him do the same thing 4 times then walk back the way he came.
I got down to investigate and discovered the thread was a bit heavy and before the thread would break it would pull tight and make a slight noise caused by the device as it moved under the pressure....so now I use very light thread for all my tricks.