When you rub plastic comb on dry hair, some electrons jump from comb to hair leaving the comb charged (Why? Another story some other day). Now when you bring the comb near the bits of pieces of paper it polarizes the paper.
Polarizes? what does it mean. It means the positive charge on the comb attracts the electrons of the electrically neutral paper and brings the electrons nearer to the comb. That means the other end develops equal positive charge. This is the polarization phenomena in which the charges get separated.
Now how does it attracts the electrically neutral bits of paper? ( yes it is still electrically neutral!!! only it has got polarized). Apply coulomb’s law i.e force inversely proportional to r square. That means the attractive forces are higher than the repulsive forces.(q1 and q2 are same but r is different). That means there is a net attractive force on the pieces of paper.
 
						

							
Dear student 
When 2 suitable bodies are rubbed, they become oppositely charged due to the transfer of electrons from one body to other. The changes remains with the bodies and so the electricity is called static electricity. As they become oppositely charged they get a tendency to attract each other. Dat is why, a plastic comb attract piece of paper when rubbed in dry hair
Good Luck