As mentioned in the previous post, dipole is referred to the unequal distribution of electrons around different atoms.
What leads to this unequal distribution?
Difference in electronegativity between atoms that form a bond.
The atom with the higher electronegativity has a greater tendency for attracting electrons. This results in a greater electron density around that atom, giving rise to a slight negative charge on that atom.
The atom with the lower electronegativity has less tendency for attracting electrons. This results in a smaller electron density around that atom, giving rise to a slight positive charge on that atom.
The result is a bond with one slightly negative end and one slightly positive end, known as a covalent polar bond!