Custom Field and rwmb_get_value hook?

I have created a Custom Field which basically saves an array. I can call this from the database using meatbox but obviously just returns the array as it should.

echo rwmb_get_value( 'x' );

Is there a way I can hook into the returned value so I can display this differently when calling 'echo rwmb_get_value( 'x' );'? e.g. to JSON or to a string