How to make subfigure letter (a, b, c, ...) colorful in the text as referenced figures?

The figures appear colorful when I refer them in the text:

See:

However, the subfigures a & b are not real/automated subfigures. They are belong to 1 figure, I type a and be manually. I want the text also pretend like the Fig. 15a all part of it.

So I want to link “a” to the figure and also at the same color, when it is print of non-print mode.

%% Use TU Delft cyan as the color for titles, unless the 'print' option is
%% specified, in which case we use anthracite, a dark gray, which is also used
%% for the thumb indices.
definecolor{anthracite}{cmyk}{0,0,0,0.8}
if@print
    colorlet{title}{anthracite}
else
    colorlet{title}{tudelft-cyan}
   %colorlet{title}{tudelft-cyan}
fi
    colorlet{thumb}{anthracite}

documentclass{article}
usepackage{subcaption}
DeclareCaptionLabelFormat{hidden}{}
captionsetup[subfigure]{labelformat=hidden}
usepackage[colorlinks]{hyperref}
begin{document}
begin{figure}
subcaptionbox{label{a}}{}%
subcaptionbox{label{b}}{}%
anything

caption{somecaption}
end{figure}

ref{a}, ref{b}
end{document}