LC-Filter for DPS5005 power supply
The best way to probe would be with a very short ground spring tip, something like this:



Let's assume the noise spike you measured is really there or at least some it is there. The width is very short on the order of nano-sec. This is typical of noise originating from very fast edges on the switch node and coupling to the output through the parasitic capacitance of the inductor. The best filter for this is a ceramic capacitor and ferrite bead as they are effective at these frequencies and the ferrite bead is largely resistive which reduces the chance of ringing. However I don't know how you plan to add such a filter to the off the shelf power supply you are using.