When my oil pressure "switch" went bad, it would simply not register any oil pressure at all; the cluster gauge was resting as if the engine was shut off. After about one minute, it shot up to its center position, indicating I had "oil pressure", as RonD has described.
In your case however, it sounds as if you may have an issue with correct engine oil pressure. You did not mention the year of your Ranger, which is important, as the earlier Rangers used a true oil pressure gauge setup, the oil gauge needle would fluctuate a bit as the engine RPM's increased/decreased. The newer Rangers only show "pressure", again as RonD has described.
Only way for you to test is first by noise, as suggested. If you hear some valvetrain clatter at idle or low RPM's, then it's most likely you have low oil pressure; not enough oil is reaching the valve train at low RPM/idle. This is a condition when the main and rod bearings become worn, allowing more oil to flow past, and therefore reducing oil pressure. I'll also assume you have oil in the pan, enough to be at least on the "add" mark of the dipstick.
If you are not hearing valve train clatter at low RPMs/idle, you can replace the oil pressure sender (or switch in newer year Rangers) and see if that corrects the gauge issue, or connect an oil pressure gauge to the hole that the factory sender/switch is in, and see first hand with this temporary setup if you are getting good oil pressure. This would be the best test, to provide piece of mind that the oil pressure is alright.