SIMH has a PDP-1 emu. But SIMH is kinda hard to use due to it using INI files for initialization of almost all devices. For example, here's my INI file I use with SIMH for my Ultrix-11 PDP-11 emu:
set rq0 rd54 ;disk controller
attach rq0 ultrix1131.disk ;attaching disk image
attach tq0 ultrix31.tap ;attaching install tape image
set cpu 11/73 4M ;configuring CPU
boot rq0 ;actual boot
And that INI is actually easy. I have more complicated ones. So, if you read the SIMH docs, you may be able to use it.