How to dump displace of atoms out?

Hello everyone,
I have done a simulation with a large amount of particles flow down a flume to a horizontal container at the bottom which already has particles in it, I want to know the displacement of the particles at the bottom. By enquiring the Manual, I found the "compute 1 all displace/atom", this command do the job of computing the displace of atom in specified group, but I don't know how to dump out the computed results. Can someone give me help? Any suggestion will be appreciate. Thanks!

Best Regards!
Qiao