Magnetic field sensor for oscilloscope
What you're after is a "B Field Probe". Usually you need to include a low noise amplifier between it and the scope as the signal strength is usually very small. 

At their simplest they are just a PCB with a connector and an optional protective coating. 

Hall effect sensors may work, but the signal strength would be so tiny I suspect it would put you down in the noise.

I actually suspect for a CCFL screen you may have an easier time with an E-Field probe, as the voltage swings tends to be fairly high. 

These sensors are directional, however if you want the 3D value, just rotate the sensor,