Adding secondary y axis in ggplot2 without scaling factor

Question

[StartR]

HI

I want to plot two y axis - one with continuous data and other with values - ranging from 0 to 7

Example:

ID IHC   FISH1  FISH2              
1   3    11.5   9.5
2   1    2.9    3.9
3   2    1.5    6.5
4   1    3.3    1.3
5   2    5.5    8.5
6   2    6.6    9.6

How can I plot secondary y axis - if it is not related to primary y axis

I want to code in R.

I want a plot like this as output

This is my code:

data %>% 
  select(ID, IHC, FISH1, FISH2) %>% 
  gather(key = "FISH_IHC", value = "FISH_val", FISH1, FISH 2, 
         IHC, -ID) %>% 
  mutate(as_factor = as.factor(FISH_IHC)) %>% 
  ggplot(aes(x = reorder(ID,FISH_val), y = FISH_val, group = as_factor), na.rm = TRUE) +
  geom_point(aes(shape=as_factor, color=as_factor)) +
  scale_y_continuous(limits = c(0, 10),
                     oob = function(x, ...){x},
                     expand = c(0, -1),
                     breaks=number_ticks(10),
                    sec.axis = sec_axis(scales::rescale(pretty(range(IHC)), 
                                                        name = "IHC"))