Quantitative analysis of capacitive pickup of 60 Hz by an oscilloscope probe
AT LOW FREQUENCIES, capacitive coupling encounters the DC_blocked nature of the "schematic" that included the resistance of the scope probe (or the resistance of the circuit), and the High Pass Filter response causes additional attenuation.

AT HIGH FREQUENCIES, capacitive coupling produces a broadband waveshape-preserving behavior. 

ALSO

A serious confusion arises when nearby pieces of metal exist. 

The coupling changes from dipole (wire to wire) coupling, to wire over a sheet.

Or to wire to wire over aheet. 

And if you have large masses of metal in the aggressor, and large masses of metal in the victim, the coupling changes again (to something well predicted by parallel_plate math.)

summary: the frequency matters, and the size and shape of metal matters.

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assume parallel_plate model ofcoupling

assume the probe is over the metal in your bench

size is 1mm by 40mm (1.6 inches) 

assume the aggressor/transmitter is 1 meer awy, in the ceiling overhead

Let us compute a capacitance, and then a displace mnt current.

C = eo * er * area / distance

C =~~~ 9 pf/meter * (1mm * 40mm) / 1,000 mm

C =  360 pf/meter  * 1/1,000 * 1mm * (1meter/1,000mm)

C = 360/1,000,000 pf = 0.36 femto farad [ 0.36 e-15 farad]

with whatever pretenses to accuracy we wish to proclaim.

Now I = C * dV/dT = C * ( 120 * 1.414 * 377 radians/second ) 

I = 0.3e-15 * (200 * 300) = 0.3e-15 * 60,000 = 18 pico Amps at 60 Hz

(we'll forbid any florescent light spikes on the power waveform)

Now you have to decide on the system frequency response. High Pass Filter?