H̱ (Unicode)

H with macron below (H̱ ẖ) transliterates:

Arabic ẖāʼ (ﺥ) (also as ḫ)
Hebrew ẖet (ח) (also as ḫ)
Egyptian hieroglyph

Unicode

Unicode ẖ U+1E96 "latin small letter h with line below" is canonically equivalent to ẖ (U+0068 U+0331).

Note that Unicode does not reserve a codepoint for a "latin capital letter H with line below". Therefore, a sequence with a combining diacritic "macron below" must be employed: H̱ (U+0048 U+0331). This lack of a precomposed character may pose a problem for some layout engines.