Based on my understanding, you want the curve to be on top of the scatter plot. This can be done using hold on with scatter plot followed by the plot of the curve. Please refer to the below example code. You can also refer to documentation of hold on for more information
figure
[X,Y,Z] = sphere(16);
x = [0.5*X(:); 0.75*X(:); X(:)];
y = [0.5*Y(:); 0.75*Y(:); Y(:)];
z = [0.5*Z(:); 0.75*Z(:); Z(:)];
scatter3(x,y,z)
hold on
[X,Y] = meshgrid(-5:0.5:5,-5:0.5:5);
Z = sin(X) + cos(Y);
surf(X,Y,Z)
