Yes, with conditions
1. What the city publishes
Gold panning and metal detecting may continue within the boundaries of Fain Park, so long as such activity is limited to – a. use of gold pans, metal detectors, and hand tools such as picks and shovels [use of motorized or mechanical equipment or mining aids … is prohibited]; b. excavations made below the high water mark of the stream channel that do not damage or disturb root systems of live vegetation and are filled in before the area is left
Source: codelibrary.amlegal.com/codes/prescottvalleyaz/latest/prescottvalley_a
2. The state rule also applies
Arizona State Parks does not allow it, as published policy. There is no regulation behind that – the state's park rules contain no metal detecting provision at all.
3. County rules
Awaiting review.