When a ball is taken from the equator to the pole of the earth:

The mass of an object is constant everywhere. However, the acceleration due to gravity ($g$) varies with location on Earth because of Earth's oblate spheroidal shape and centrifugal force from rotation. The value of $g$ is minimum at the equator and maximum at the poles. Since weight is given by $W=mg$, moving a ball from the equator to the pole increases the value of $g$, causing its weight to increase.