If you want to run a job on a server, you can start a new tmux session, detach from it and attach back at a later point of time.
Starting a tmux session within a tmux:
tmux new -s [name]
Detaching from this session:
Detach STRG-B d
Display the active session:
tmux ls
Attaching to the session:
tmux attach -t [name]
Have fun!