how is calorie related to heat capacity
The heat capacity (C) of a body is the proportionality constant between the heat absorbed or lost (ΔQ) to the surrounding and the resulting change in temperature (ΔT).
Thus,
ΔQ = C ΔT
,
Calorie is the unit of energy i.e used to measure the amount of energy.
It is the amount of heat required to raise the temperature of one gram of water by 1°C.