The dipole moments of C C l 4 , C H C l 3 and C H 4 are in the order

In ${\mathrm{CHCl}}_3$, dipole moment of $\mathrm{C}-\mathrm{H}$ is added to the resultant dipole moment of three $\mathrm{C}-\mathrm{Cl}$ bonds, hence compound has non-zero value of dipole moment.

Electronegativity of carbon $=2.5$
Electronegativity of hydrogen$=2.1$.


Elelctrongegativity of $\mathrm{C}=2.5$
Electronegativity of $\mathrm{Cl}=3$

Due to symmetry and similar bonds, vector summation of net dipole moments of both ${\mathrm{CH}}_4, {\mathrm{CCl}}_4$ are zero, hence equal.