But really, from the putty's perspective, it has little ferrous particles suspended in it. Just like paperclips and magnets, it wants to attract to the magnet. Since the ball has a magnetic field that surrounds it, in this case who knows what that field looks like probably a normal polar field based on its movement but who knows. The metal particles in the putty want to align with that field, just like a bar magnet and iron filings. Since magnetic fields dissipate at the square of their distance, every inch is exponentially weaker in field strength. So the putty can only be manipulated close to the magnet, and just like paperclips or iron filings, each particle helps pass on the effect to the ones surrounding it, they then push the particle in front further up to help it overcome the putty.