If at the time of exercise, the price of the underlying asset is higher than the breakeven price, the call option is considered In The Money. In this case, the user is entitled to the payoff, which is equal to the strike price of the underlying minus the spot price. This difference is calculated automatically and settled in the underlying asset (the quote token) to the option buyer.
Example: A user buys a 2 ETH/DAI call option, at a strike price of 3,500 DAI. At the time of exercise, the ETH price is 4,000 DAI. User receives the difference between the strike price and the spot price (4,000 - 3,500), multiplied by the amount of options they own (2). In this case, the user is entitled to 1,000 DAI, which is settled in ETH. Thus the user receives (1,000/4,000 ETH) = 0.25 ETH on exercise.