Yes, women can use a Hajj sun cap or niqab during Hajj and Umrah, provided it aligns with the requirements of Ihram. Here are a few considerations to keep in mind:

Ihram Requirements for Women: During Hajj and Umrah, women are required to cover their heads, but not their faces. While men cannot cover their heads, women can, making a sun cap or a head-covering scarf an acceptable and practical choice