What is the ruling on selling and maintaining computer and phone parts that are likely to be used for unlawful purposes, is the income earned from that considered Haram, and what should the seller do in this case?

The basic principle concerning the sale and maintenance of devices that can be used for both lawful and unlawful purposes—such as phones and computers—is permissibility. The seller is not required to investigate how the buyer will use them, even if the buyer's apparent state suggests a lack of commitment [to religious obligations]. Furthermore, the claim that 90% of Muslims use these devices for unlawful purposes requires proof. However, if the seller or technician strongly believes that the buyer will use the device for unlawful purposes, then it is not permissible to sell it to him or to repair the device.