Using a phone during তাওয়াফ is permissible when the phone is being used as a tool to aid the worship — such as reading কুরআন from a কুরআন application, accessing a dua collection, or using a counter app to track the circuits of তাওয়াফ. These are modern tools that serve the same purpose as a printed dua book, which scholars have always permitted during তাওয়াফ. Reading from a book during তাওয়াফ was practiced by some of the Salaf.
Sheikh Ibn Uthaymeen, while he did not address smartphones specifically, stated that reading duas from a book during তাওয়াফ is permissible. By extension, contemporary scholars permit using a phone application for the same purpose. The key is that the phone is being used for worship-related purposes, not for worldly distractions.
However, scholars unanimously discourage non-worship phone use during তাওয়াফ: taking or making phone calls, sending messages, browsing social media, or taking selfies. These activities distract the হাজী from the remembrance of Allah, which is the primary purpose of তাওয়াফ. The Permanent Committee has advised হাজীগণ to minimize distractions during the rites and to focus their hearts and minds on worship. If a phone call is genuinely urgent, the হাজী may step aside, as breaks during তাওয়াফ are permissible, take the call, and then resume their তাওয়াফ from where they stopped.