I finally found the function within the ggpubr package.
Its called ggscatterhist and does the trick:
https://rpkgs.datanovia.com/ggpubr/reference/ggscatterhist.html
Scatter Plot with Marginal Histograms
Basic scatter plot with marginal density plot
ggscatterhist(iris, x = "Sepal.Length", y = "Sepal.Width", color = "#00AFBB", margin.params = list(fill = "lightgray"))