I have power 220/240 hardwired to outside pool filter. I want to add an outlet 120v nearby to plug in the pool cleaning robot or a radio, etc. The pool filter and new outlet should be able to be turned on at the same time. I do not want to dig a new trench and run a new line for the outlet. Can an electrician make changes to the existing line/ hardwire setup to add the new outlet? Other Options? Thank you

Anything near a pool has to be on a ground fault protected circuit.

Codes vary so we need to know your location.

A 120 volt receptacle will need a neutral. The existing 240 volt line to the pump will probably not have a neutral.

Plus the breaker, which should be a 2 pole GFI breaker, supplying the pump probably is not setup for serving 120 volts also.

An electrician will need to look at your situation and determine what if anything can be done.

The answer, I suspect, will be happy digging.