${\mathrm{CH}}_3\mathrm{Cl}$ has more dipole moment than ${\mathrm{CH}}_3\mathrm{F}$ because:

chlorine has higher electronegativity than fluorine

the charge separation is larger in ${\mathrm{CH}}_3\mathrm{Cl}$ compared to ${\mathrm{CH}}_3\mathrm{F}$

Electron affinity of chlorine is greater than that of fluorine

the repulsion between the bond pairs and non-bounded pairs of electrons is greater in ${\mathrm{CH}}_3\mathrm{Cl}$ than ${\mathrm{CH}}_3\mathrm{F}$