The value of a $3\times 3$ determinant is $3$. The value of the determinant formed by its cofactors is:

Let the determinant be $|A|$. The determinant formed by the cofactors of $|A|$ is equal to $|adjA|$.We know the property:
$$|adjA|=|A{|}^{n-1}$$
Here, $|A|=3$ and $n=3$.
$$|adjA|=3^{3-1}=3^2=9$$
The value of the determinant formed by its cofactors is $9$.