In \textbar{}text\textbar{} mode. Still in \textbar{}text\textbar{} mode
In |math| mode: |\hat{}. In \textbar{}text\textbar{} mode inside math mode
Still in |math| mode In \textbar{}text\textbar{} mode: \textbar{}\^.
The symbol can be only in math: \ensuremath{\longleftarrow{}} $a<b$
$$c>d$$
$$ unicode mapping in math mode:
in text:  \ensuretext{\textexclamdown{}}
in mixed: \hat{a}
in math:  \longleftarrow{}
none:     \unicodechar{1911} $$
unicode mapping in text mode:
in text:  \textexclamdown{}
in mixed: \^{a}
in math:  \ensuremath{\longleftarrow{}}
none:     \unicodechar{1911}