\begin{figure}[H]  % I have included float package for the H
\centering
\subfigure[]{
\includegraphics[width=0.45\linewidth]{figure.png}
\label{sublable01}
}
\subtable[]{
\begin{center}
\begin{longtable}[ht]{@{\extracolsep{\fill}}p{0.15\textwidth}p{0.15\textwidth}p{0.15\textwidth}@{}}
\toprule
		\textbf{From} & \textbf{To} & \textbf{Distance (in cm)}\\
\midrule
		  Robot Base & First Dot & 26 \\

		  First Dot & Second Dot & 12.5 \\

		  Second Dot & Third Dot & 21 \\

		  Third Dot & Fourth Dot & 23 \\

		  Fourth Dot & Fifth Dot & 38 \\

		  Fifth Dot & Sixth Dot & 62 \\

		  Sixth Dot & Seventh Dot & 137 \\
\bottomrule
\end{longtable}
\end{center}
\label{sublable02}
}
\caption[]{\subref{sublable01}: description of figure. \subref{sublable02}: description of table.}
\label{mainlabel}
\end{figure}