Retrieve CPU usage and memory usage of a single process on Linux?

Question

I want to get the CPU and memory usage of a single process on Linux - I know the PID. Hopefully, I can get it every second and write it to a CSV using the \'watch\' command

Answer 1

For those who struggled for a while wonderring why the selected answer does not work:

ps -p  -o %cpu,%mem

No SPACE ibetween %cpu, and %mem.