import ROOT
import numpy as np

c1 = ROOT.TCanvas("c1","hists with different scales",600,400)

ROOT.gStyle.SetOptStat(False)

h1 = ROOT.TH1F("h1","my histogram",100,-3,3)

h1.Fill(np.array([ROOT.gRandom.Gaus(0, 1) for _ in range(10000)]))

h1.Draw()
c1.Update()

hint1 = ROOT.TH1F("hint1","h1 bins integral",100,-3,3)

sum = 0
for i in range(1,101) :
   sum += h1.GetBinContent(i)
   hint1.SetBinContent(i,sum)

rightmax = 1.1*hint1.GetMaximum()
scale = ROOT.gPad.GetUymax()/rightmax
hint1.SetLineColor("kRed")
hint1.Scale(scale)
hint1.Draw("same")

axis = ROOT.TGaxis(ROOT.gPad.GetUxmax(),ROOT.gPad.GetUymin(),
      ROOT.gPad.GetUxmax(), ROOT.gPad.GetUymax(),0,rightmax,510,"+L")
axis.SetLineColor("kRed")
axis.SetLabelColor("kRed")
axis.Draw()