How to combine two Unicode symbols to create a new symbol?

Question

I want to create a new symbol that combines an "Latin small letter o" and the diacritic symbol for "low line."

Latin small letter o is U+006F

Diacritic low line is U+0332.

The desired result would have a line below the o. It is the opposite of "Latin capital letter O with Macron" (http://www.fileformat.info/info/unicode/char/014c/index.htm) except that the line is equal to the width of the 0.

How to combine U+006F and U+0332 for use with JSON (e.g. \u006F and \u0332) and for use with HTML hex (e.g. o and ̲)

Answer 1

Based on this quesion: What's the unicode glyph used to indicate combining characters?

the answer for HTML and JSON basically is the same: concatenate sans space.

HTML entities: o̲

JSON: \u006F\u0332