I solved this by making a Vehicle.
1. attach the object to the rope.
2. create a vehicle that can create a rope. (check vehicle list here : https://community.bistudio.com/wiki/ropeCreate/transport)
3. And create a rope in the Vehicle.
4. then attach created Vehicle to object.
It's not the best solution, but it looks pretty good if you adjust the offset well.
_ropeUp = ropeCreate[_vehicle,[0,0,0],_length];
private _glue = "PaperCar" createVehicle [0,0,0];
_glue allowDamage false;
_ropeDown = ropeCreate [_glue,[0,0,0],0];
_glue attachTo [_unit,[0,0,0]];
[_unit,[0,0,0]] ropeAttachTo (_ropeUp);
If you want to place an object on the top of the rope, decrease the length of the _ropeUp and increase the length of the _ropeDown . If you want to place an object at the bottom of the rope, do the opposite.