etc/systemd/system/xscreensaver.service

   1 [Unit]
   2 Description=Lock X session using xscreensaver
   3 Before=sleep.target
   4
   5 [Service]
   6 User=siraaj
   7 Type=forking
   8 Environment=DISPLAY=:0
   9 ExecStart=/usr/bin/xscreensaver-command -lock
  10
  11 [Install]
  12 WantedBy=sleep.target