How can i obtain the x-px distribution of particles at the same time?

Good afternoon! I don’t know how to output the x-px distribution of the particles at a certain time. Is there an option to calculate the result according to the time step in the new version of Geant4? Or is there any other possible way that I can get the x-px distribution of the particle at one point in time? I would appreciate it if you could give me an answer.