## Frequentist MCMC

Hi,
I am a biologist and I am trying to get my head around MCMC. I have found enough information to understand MCMC in the Bayesian framework but I cannot find much information on frequentist MCMCs.
What would be the equivalent of the following R code in using ML MCMC?

It is an example I found online and it is not homework.

n is the sample size and the mean of x is 3.508. A random variable X is assumed to be normally distributed where mu is unknown and sigma=0.01. The prior on the mu parameter is represented with a normal distribution with pmu=3.5 and psigma=1.