Python ROC curve from two discrete histogram distributions

I am using Python (NumPy) and I want to plot a ROC curve given a 1D noise histogram and another 1D histogram for the signal + noise distribution. I know that various libraries like scikit-learn can generate ROC curves, but they use a supervised machine learning approach based on predicted and actual labels. Instead, I have 2 numpy arrays: 1 for the discrete probability density function (histogram) of the background noise distribution and another histogram for the signal + noise distribution. I am not doing machine learning, instead I just want to make an ROC curve from two histograms. Can scikit-learn or another python library do this?

thank