Answer
$1.08 \ J$
Work Step by Step
The work required to compress the spring beyond equilibrium can be calculated as:
$\text{Work}, W= \int_{m}^{n} kx \ dx $; where $k$ is the spring constant.
and $\dfrac{1}{2} k(0.2)^2=12 \implies k =600 \ N/m$
Now, $W= \int_{m}^{n} kx \ dx\\= \int_{0}^{0.06} 600 \ x \ dx\\=600 [\dfrac{x^2}{2}]_{0}^{0.06} \\=(600) \times [\dfrac{(0.06)^2}{2}] \\=1.08 \ J$
