Bitcoin is a decentralised cryptocurrency so you can not Buy/Sell or Exchange directly yourself, you must need to use Exchange service like Pay Exchanger. Buying Bitcoin is very easy in Pakistan, you get bitcoin by Local Bank Transfer (PKR), By Paying cash physically or even by mobile payment methods like EasyPasa, Mobicash etc.
Before buying make sure you are getting good bit coin rates. Profits.pk displays live Bitcoin and Altcoin prices. Please visit the below link to see latest Bitcoin and Altcoin prices such as Ethereum, Litecoin, IOT and all other digital currencies.
Firstly create account and register at PayExchanger.
Pay exchanger also accepts bank transfer and cash(Limited cities only).
Alternatively, you can also buy from other available local exchanges such as localbitcoins.com, Remitano.com and Urdubit.com.